Even if you're not usually frightened by snakes, it's hard not to feel intimidated by a Gaboon Viper (Bitis gabonica). Just look at its skull. With fangs that can reach up to five centimeters in length, Gaboons are reportedly the largest vipers on earth, and the toothiest of all venomous snakes.

"The Gaboon viper is just weird. So delicate," explains Simon Winchester, author of the newly published — and aptly named — photobook, Skulls. "It looks dangerous even as a skull, with its great big fangs."